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Expanded very large array continuum observations toward hot molecular core candidates

journal contribution
posted on 2023-05-17, 08:11 authored by Hofner, P, Kurtz, S, Simon Ellingsen, Menten, KM, Wyrowski, F, Araya, ED, Loinard, L, Rodriguez, LF, Cesaroni, R
We have used the Expanded Very Large Array (EVLA) with two 1 GHz wide bands to obtain K-band (1.3 cm) continuum observations toward the following five hot molecular core candidates: IRAS 18151 – 1208, IRAS 18182 – 1433, IRAS 18345 – 0641, IRAS 18470 – 0044, and IRAS 19012 + 0536. The sources were selected from the 2002 list of Sridharan et al. and are characterized by high FIR luminosity, dense molecular and dust condensations, massive large-scale CO flows, and the absence of strong cm continuum emission. These properties are indicative of massive star-forming regions in an evolutionary phase prior to ultra- or hypercompact H II regions. We detect a total of 10 individual 1.3 cm continuum sources toward this sample, and derive in-band spectral indices between 19.3 and 25.5 GHz consistent with thermal free-free emission, for all sources except component A in IRAS 18182 – 1433, which has a negative spectral index indicative of synchrotron emission. We suggest that in most cases the 1.3 cm sources are due to shock-induced ionization, rather than direct photoionization by massive objects. The momentum rate present in these ionized flows is sufficient to drive the large-scale molecular flows. We discuss a number of morphological features supporting this hypothesis. The present observations demonstrate that the EVLA has sufficient sensitivity to study the regions near very young massive stars in the cm continuum.

History

Publication title

The Astrophysical Journal Letters

Volume

739

Article number

L17

Number

L17

Pagination

1-4

ISSN

2041-8205

Department/School

School of Natural Sciences

Publisher

Institute of Physics Publishing Ltd

Place of publication

United Kingdom

Rights statement

Copyright 2011 The American Astronomical Society

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the physical sciences

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